presentation for undergraduate, in medical school

1. Vibrio cholerae and Non-cholera vibrios
Facilitators: Dr Salim Masoud.
Daniel Mwandu

2. Presentation outline
• Introduction
• General properties
• Transmission
• Pathogenesis
• Clinical features
• Diagnosis
• Treatment,
• Epidemiology, prevention and control

3. INTRODUCTION
• The genus Vibrio are naturally habitant of marine
and estuarine aquatic ecosystems.
• It composed of more than 150 species, including
three species human pathogens(V. cholerae, V.
parahaemolyticus, and V. vulnificus)
• V. cholerae was first discovered as a causative
agent of cholera in 1854 by Italian physician
Filippo Pacini.
• The genus name given refers its vibrate moving

4. The medically important Vibrios

5. GENERAL CHARACTERISTICS
• Comma-shaped, gram negative, curved rod 2–4
µm long
• It is actively motile by using singular polar
flagellum.
• Reduce nitrate into nitrite, Catalase and Oxidase
positive except V. metschnikovii.
• Vibrios grow at a very high pH (8.5–9.5). and are
rapidly killed by acid.
• They are halophilic and facultative anaerobes

6. • APW and Cary blair are used as transport media
due their Alkaline condition.
• They grow well TCBS, although other routine
media can be used to recover.
• On TCBS ,sucrose fermenter like V. cholerae
produces yellow colonies with opaque center
• But non sucrose fermenter produce green to
blue-green colonies eg V.parahemolyticus

9. Vibrio cholerae

10. Vibrio cholerae classification
• Vibrio cholerae is divided into more than 200 serogroups
determined by the structure of the O-antigen of LPS.
• strains belonging to serogroups O1 and O139 can cause
cholera and epidemics due to their ability to produce
cholera toxin (CTX).
• non-O1/non-O139 serogroup cause small gastroenteritis
outbreaks, sporadic cases of bacteremia, and wound
infections,
• more than 85% of non-O1 serogroups (including O139)
have a capsule that is critical for virulence in
extraintestinal infections

12. TRANSMISSION
• Cholera is transmitted by the fecal-oral route
through ingestion of contaminated water or food.
• it require high infective dose of ≤1010organisms in
normal gastric acid and 102-104 in person with
decreases stomach acidity
• Other Vibrio species can cause a skin infection
when an open wound is exposed to salt water

13. PATHOGENESIS

14. Clinical features
• The clinical manifestations of cholera begin an
average of 2 to 3 days after ingestion of the
bacteria (can be <12 hours),
• Its characterized by profuse rice watery diarrhea
and vomiting.
• This resulting electrolyte loss and dehydration.
• The mortality rate is high( 70%) in untreated
cases but less than 1% in well managed
patients.

15. DIAGNOSIS
• Presumptively diagnosed based on clinical
suspicion in patients who present with severe
acute watery diarrhea.
• Liquid stool or rectal swab are collected for
laboratory diagnosis
• The diagnosis can be confirmed by isolation of
V. cholerae from stool cultures performed on
specific selective media(TCBS).

16. Cont..
• Isolates from stool culture are determined for O1
serotype using polyvalent antisera for V.
cholerae O1.
• If desired, confirm identification with Inaba and
Ogawa antisera.
• If specimen is not serotypeable, consider, V.
cholerae O139.
• Molecular technique (PCR) can be used

17. TREATMENT
• Rehydration by using ORS and Ringer Lactate
solution or 0.9% sodium chloride solution.
• Antimicrobial agents play a secondary role in
patient management eg doxycycline,
ciprofloxacin and Azithromycin or Erythromycin
• Zinc and Folic Acid Supplements for children
less than 6 months.

18. EPIDEMIOLOGY, PREVENTION
AND CONTROL
•

19. WHO: Cholera in Tanzania

20. WHO: Outbreak of 2022 in Tanzania.

21. MoH: Outbreak of 2023 in Dar es salaam

22. PREVENTION AND CONTROL
• Mobilize and health education to community for
early case detection and treatment.
• Work with community leaders to limit the number
of large gatherings, if seen mandatory, establish
by-laws
• Ensure availability and continuous access to
clean and safe water.

23. • Promote safe preparation of food, including
fruits, and vegetables
• Promote safe disposal of human waste.
• Cholera Vaccine is available however its
utilization must be accompanied with strategies
to improve water and sanitation

24. Non Cholera
Vibrios

25. Vibrio
parahaemolyticus

26. Introduction
• Vibrio parahaemolyticus causes acute
gastroenteritis following ingestion of contaminated
seafood such as raw fish or shellfish, clams, and
oysters.
• It is a halophilic bacterium, grows well in
concentrations of NaCl as high as 6-8%.
• Resemble V. cholerae in feature but does not
ferment sucrose.(their colonies on TCBS apper
green to blue-green)

27. Introduction
• V. parahaemolyticus is also associated with the
Kanagawa phenomenon, are haemolytic on blood
agar plates, while those isolated from non-human
sources are non-haemolytic.
• V. parahaemolyticus is ubiquitous in coastal waters,
• It is the most common cause of bacterial
gastroenteritis in Japan and Southeast Asia.
• also is the most common Vibrio species responsible
for gastroenteritis in the United States.

29. Currently situation
place Case Period
kigoma 137 April-may 2022
katavi 124 April-may 2022

30. Pathogenesis
• Pathogenicity of V. parahaemolyticus it is
strongly linked to production of a
thermostable direct hemolysin (TDH),
• Also known as Kanagawa hemolysin,
• An important method for classifying virulent
strains of V. parahaemolyticus is detection of this
hemolysin, which produces β-hemolytic colonies
on agar media with human blood but not sheep
blood.

31. Pathogenesis
• The virulent strains of V. parahaemolyticus are
referred to as Kanagawa positive
• Moreover they have type III secretion
systems that mediate bacterial survival and
expression of virulence factors.
• TDH induces enterotoxicity lead to chloride ion
secretion in epithelial cells by increasing
intracellular calcium.

32. Clinical features
• Gastroenteritis, the disease develops after a
5- to 72-hour incubation period, with
explosive watery diarrhea.
• Profuse watery diarrhea free from blood or
mucus accompanied with Headache,
abdominal cramps, nausea, vomiting, and
low-grade.
• Wound infections occur to people exposed
to contaminated seawater.

33. Treatment
• V. parahaemolyticus gastroenteritis is
usually a self-limited disease,
• Antibiotic therapy can be used in
addition to fluid and electrolyte therapy
in patients with severe infections

34. Prevention
• Do not eat raw oysters or other raw fish.
• Freezing of sea water fish immediately after
harvesting.
• Avoid exposure of open wounds or broken
skin to warm salt or brackish water

35. Vibrio vulnificus

36. Introduction
• Vibrio vulnificus is an emerging pathogen of
humans.
• Commonly found in the gulf of Mexico.
• It affect mostly immunocompromised people..
• It is primarily known to cause severe wound
and soft tissue infections.
• V. vulnificus is the most common cause of Vibrio
septicemia.

38. Pathogenesis
• In the presence of gastric acids, V. vulnificus rapidly
degrades lysine, producing alkaline by products.
• They produce acidic polysaccharide capsule which
enable to evade the host immune response by
inducing macrophage apoptosis.
• V. vulnificus also possesses surface proteins that
mediate attachment to host cells and secretes
cytolytic toxins leading to tissue necrosis.

39. Clinical manifestations
• Primary septicemia present with a sudden
onset of fever and chills, vomiting, diarrhea,
and abdominal pain.
• Gastroenteritis-associated with ingestion
• Secondary skin lesions/ wound infections
with tissue necrosis are often present.

40. Reference
1. Jawetz, Melnick, & Adelberg’s: Medical Microbiology,
Twenty-Eighth Edition; 2019.
2. Murray: Medical Microbiology, ninth Edition; 2021.
3. David A. Montero et al; Vibrio cholerae, classification,
pathogenesis, immune response, and trends in vaccine
development. Front. Med., 05 May 2023 Sec. Infectious
Diseases: Pathogenesis and Therapy
| https://doi.org/10.3389/fmed.2023.1155751

41. THANK YOU
For your Time